Understanding Antiphospholipid Syndrome

Table of Contents

1. Risk Factors for Antiphospholipid Syndrome
2. Diagnosing Antiphospholipid Syndrome
3. Antiphospholipid Syndrome Symptoms
4. Blood Clots
5. Pregnancy Complications
6. Neurological
7. Treating Antiphospholipid Syndrome

Antiphospholipid syndrome (APS) is a rare autoimmune disease that causes the body to abnormally form blood clots. There are about 40 to 50 cases per 100,000 people, and women are three to four times more likely to have APS than men. Patients with systemic autoimmune conditions, like lupus, may also get APS.

When someone has APS, the immune system makes antibodies that attack proteins in the blood. These proteins bind to phospholipids, which are important for cell membranes to work correctly and provide protection. When the body starts fighting normal proteins, blood clotting starts. Blood clots then form in the vessels. APS can also cause problems for pregnant women, like frequent miscarriages. 

APS can be further grouped as primary or secondary. Primary APS occurs on its own, without another autoimmune disorder. Secondary APS occurs with another autoimmune disease, like lupus.

Risk Factors for Antiphospholipid Syndrome

Researchers don’t exactly know why people develop APS, but there are some known risk factors for the condition, including:

• Having another autoimmune disease, like lupus
• Family history of the disease
• Female sex
• Bacterial or viral infections, like HIV or Lyme disease
• Use of some drugs, including antibiotics and anti-seizure medicines

Diagnosing Antiphospholipid Syndrome

To diagnose APS, clinicians ask about your health, do a physical check-up, and run lab tests. The criteria for diagnosing APS include at least one symptom, like a blood clot or complications with pregnancy, and a lab test to confirm that antibodies associated with the condition are in your blood.

The lab findings will have one of these antibodies present:

• Lupus anticoagulant (LAC)
• Anticardiolipin antibodies (aCL)
• Beta2-glycoprotein I antibodies

If a lab test shows positive results, you’ll take another test 12 weeks later. The test is repeated because medications or infections can cause antibodies to appear, leading to a false-positive result.

In 2023, the American College of Rheumatology and the European Alliance of Associations for

Rheumatology released new criteria for diagnosing APS. These changes include a list of more detailed symptoms and improved lab tests, which help clinicians better diagnose APS.

Antiphospholipid Syndrome Symptoms

APS can cause a variety of symptoms due to blood clots forming in different parts of the body. The severity and type of symptoms can vary widely. Common symptoms include blood clots, problems during pregnancy, and issues with the brain and nerves. The symptoms can be different for each person and can affect many parts of the body.

Blood Clots

Patients with APS tend to get blood clots often, even while taking blood thinners. Two types of blood clots that often occur in patients with APS include DVT (deep vein thrombosis, a blood clot in a deep vein) and PE (pulmonary embolism – a blood clot in the lungs). DVT can cause pain and swelling in the affected part of the body, while PEs often cause shortness of breath, chest pain, and fatigue.

Pregnancy Complications

APS can cause frequent miscarriages in the second or third trimester of pregnancy. Other pregnancy-related problems might include slower fetal growth, fetal distress, problems with the placenta, and preclampsia.

Neurological

A blood clot in the brain can lead to a stroke or transient ischemic attack (TIA). A TIA can cause symptoms similar to a stroke that lasts for a short time. Sometimes, patients may also have seizures or muscle movements that they can’t control. A clot blocking the retinal artery or vein in your eye can affect vision.

APS symptoms can be different for each person. Some patients might not have symptoms and only have antibodies in their blood. If multiple organs are affected, some patients may have more severe symptoms.

Treating Antiphospholipid Syndrome

The goal of APS treatment is to prevent more blood clots from forming and stop current blood clots from getting larger. Treating APS involves using blood thinners, also called anticoagulants. The type of blood thinner used, and the length of treatment, will depend on each patient’s situation.

Treatment options may include:

• Warfarin to prevent clots
• Aspirin or clopidogrel (Plavix^®) to make the blood less sticky and prevent clots
• Pregnant women might need heparin, low-dose aspirin, corticosteroids, or a type of medicine called intravenous (IV) immunoglobulin to help control the immune system and prevent miscarriages
• Patients with antibodies in their blood but no symptoms may need aspirin

Direct oral anticoagulants (DOACs), which include blood thinners like apixaban (Eliquis^®) and rivaroxaban (Xarelto^®), are less effective than warfarin in preventing recurrent blood clots in patients with APS – that’s why warfarin is typically used instead.

Some patients who are at risk of APS but don’t have a diagnosis may need to change their diet, drink more water, and increase exercise. Quitting smoking is also strongly recommended since smoking harms blood vessels (and many other parts of the body).

The bottom line: APS is a rare autoimmune disease that makes blood more likely to clot. While there’s no cure, treatment—usually with blood thinners—can help prevent further complications.

*Originally published in The Beat — August 2024. Read the full newsletter here.